1. Field of the Invention
The present invention relates to improvements in index tabs for use on divider sheets, filing cards and the like. More particularly, the present invention relates to index tabs that are easy to align along the edge of a divider sheet and easy to affix thereto.
2. General Background and State of the Art
Index tabs comprising a piece of material folded over upon itself to form a double ply tab having adhesive on its inside edges have been used extensively in the past. A number of problems are associated with the use of such tabs. These problems include difficulties with alignment and with adhering the tabs to divider sheets or other tab-bearing media.
A prior art index tab having a projecting bead on an adhesive covering skirt is disclosed in U.S. Pat. No. 2,541,791 (Taylor). The projecting bead is located on the skirt-covering adhesive on one side of the tab. The projecting bead is disposed such that the sheet of paper upon which the index tab is to be mounted is projected between the inner faces of the tab. The projecting bead can then be used to align that side of the tab with the edge of the mounting sheet, before the skirt is removed to expose the adhesive. There are several problems inherent to the tab design. For example, the projecting bead may become crushed or otherwise lose its rigidity and form if the two sides of the tab are pressed together. More importantly, the projecting bead allows for only one side of the index tab to be aligned with the mounting sheet. The other side of the index tab is left free, such that it cannot be easily aligned with the mounting sheet or with the other, mounted, side of the index tab. Therefore, the index tab may be unevenly mounted upon the mounting sheet. Additionally, as the skirt is removed to expose the adhesive, the projecting bead is necessarily removed. Thus, the alignment means is actually removed as the adhesive is exposed, such that when the tab is applied it may no longer be aligned with the mounting sheet at all.
U.S. Pat. No. 1,983,878 (Rand) discloses several index tab constructions having shoulders which form a catch or stop for positioning the index tab on a mounting sheet. Unfortunately, many of the shoulder constructions cause the tab portion of the index tab to lie outside of the plane of the mounting sheet. Additionally, all of the shoulder constructions provide a shoulder that is not attached to both lower tab extensions. That is, when the tab extensions are separated, such as to apply the tab to a mounting sheet, the edge of the mounting sheet may be inserted past the shoulder, to the very top of the tab. To prevent this, the tab extensions must be kept close together, to ensure that the shoulder engages the edge of the mounting sheet. This need to carefully control the separation of the tab extensions during the mounting procedure makes the procedure cumbersome.